Laboratory water bath

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A water bath operating at 72°C
Inside a shaking water bath

A water bath is laboratory equipment made from a container filled with heated water. It is used to incubate samples in water at a constant temperature over a long period of time. Most water baths have a digital or an analogue interface to allow users to set a desired temperature, but some water baths have their temperature controlled by a current passing through a reader. Utilisations include warming of reagents, melting of substrates or incubation of cell cultures. It is also used to enable certain chemical reactions to occur at high temperature. Water bath is a preferred heat source for heating flammable chemicals instead of an open flame to prevent ignition.[1] Different types of water baths are used depending on application. For all water baths, it can be used up to 99.9 °C.[2][3] When temperature is above 100 °C, alternative methods such as oil bath, silicone bath or sand bath may be used.[4]

Precautions[edit]

  • Use with caution.
  • It is not recommended to use water bath with moisture sensitive or pyrophoric reactions.[5] Do not heat a bath fluid above its flash point.[5][6]
  • Water level should be regularly monitored, and filled with distilled water only.[7][8] This is required to prevent salts from depositing on the heater.[8]
  • Disinfectants can be added to prevent growth of organisms.[6][7]
  • Raise the temperature to 90 °C or higher to once a week for half an hour for the purpose of decontamination.[6]
  • Markers tend to come off easily in water baths. Use water resistant ones.
  • If application involves liquids that give off fumes, it is recommended to operate water bath in fume hood or in a well ventilated area.[9]
  • The cover is closed to prevent evaporation and to help reaching high temperatures.[9]
  • Set up on a steady surface away from flammable materials.[6]

Types of water bath[edit]

A shaking water bath in action

Circulating Water Baths[edit]

Circulating the water baths (also called stirrers [10]) are ideal for applications when temperature uniformity and consistency are critical, such as enzymatic and serologic experiments. Water is thoroughly circulated throughout the bath resulting in a more uniform temperature.

Non-Circulating Water Baths[edit]

This type of water bath relies primarily on convection instead of water being uniformly heated. Therefore, it is less accurate in terms of temperature control. In addition, there are add-ons that provide stirring to non-circulating water baths to create more uniform heat transfer.[4]

Shaking Water Baths[edit]

This type of water bath has extra control for shaking, which moves liquids around. This shaking feature can be turned on or off. In microbiological practices, constant shaking allows liquid-grown cell cultures grown to constantly mix with the air.

Some key benefits of shaking water bath are user-friendly operation via keypad, convenient bath drains, adjustable shaking frequencies, bright LED-display, optional lift-up bath cover, power switch integrated in keypad and warning and cut-off protection for low/high temperature.

Additional images[edit]

See also[edit]

References[edit]

  1. ^ Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. National Academy Press, Washington, D.C. 1995. p. 95. doi:10.17226/4911. ISBN 978-0-309-05229-0.
  2. ^ "Thermo Scientific Precision and Lab-Line Water Baths" (PDF). thermoscientific.com.
  3. ^ "General Water Baths" (PDF). labwit.com.
  4. ^ a b "Baths and Circulators" (PDF). pubs.acs.org. October 2004.
  5. ^ a b "Standard Operating Procedure: Heat Sources and Heating Baths" (PDF). naples.cc.sunysb.edu. February 2013.
  6. ^ a b c d T.Mahajan, Devidas; Mohammad, Indira G. Shibi,Noor; Azharuddin, Quazi Syed; Masand, Vijay H. (2015-04-16). Chemistry Laboratory Safety Manual. BookRix. ISBN 9783736887664.
  7. ^ a b "Standard Operating Procedures Manual: Biosafety Level 2 Laboratory, Arizona State University".
  8. ^ a b Cheesbrough, Monica (2005-09-08). District Laboratory Practice in Tropical Countries. Cambridge University Press. ISBN 9780521676304.
  9. ^ a b "Fisher Isotemp Water Baths" (PDF). www.seas.upenn.edu. Retrieved 2015-07-09.
  10. ^ "Water Baths, Stir and Hot Plates" (PDF). library.ewh.org.